The present invention relates to a process for sterilizing an adsorbent, and more particularly to a process for sterilizing an adsorbent for use in extracorporeal circulation treatment comprising a water-insoluble support and a sulfated polysaccharide attached to the support. The invention also relates to an adsorption column for use in extracorporeal circulation treatment having an improved storage stability.
Hitherto, for the purpose of selectively removing harmful substances from body fluid such as blood, it has been attempted to use an adsorbent comprising a water-insoluble support and, attached thereto, a material having a peculiar affinity for harmful substances, namely the so-called ligand, in extracorporeal circulation treatment. Sterilization of the adsorbent is indispensable for using it in the treatment. From the viewpoints of safety and handling upon use, sterilization by chemical reagents is inadequate and high pressure steam sterilization is preferred. However, the high pressure steam sterilization of adsorbents has the drawback that the ligand is deactivated or released from the support. In particular, it is known that for an adsorbent having a sulfated polysaccharide as a ligand is easy to cause decomposition such as desulfation by high pressure steam sterilization. If the water-insoluble support/sulfated polysaccharide adsorbent is sterilized under severe conditions, for example, at 121.degree. C. for 20 minutes, the fixed sulfated polysaccharide is hydrolyzed to release from the support, thus the ability of removing harmful substances from body fluid is deteriorated.
An adsorbent is packed in a column with a packing fluid and is used for extracorporeal circulation treatment. Water is usually used as a packing fluid by the reasons that the use of water makes it unnecessary to dry the adsorbent which is usually steam-sterilized and is obtained in a wet state and that a packing fluid in an adsorption column is always once replaced with water before using in extracorporeal circulation treatment.
There is a case where the thus prepared adsorption column for extracorporeal circulation treatment is used after storing for a period as long as about 1 year. Therefore, it is required that the adsorbent performance is maintained for at least about 1 year.
The water-insoluble support/sulfated polysaccharide adsorbent has also another defect that when a column for extracorporeal circulation treatment use packed with the adsorbent and water is stored for a long term, the sulfated polysaccharide is hydrolyzed to release from the support and, moreover, the progress of the hydrolysis produces sulfuric acid compounds and they further accelerate the hydrolysis, thus resulting in deterioration of column performance.
It is an object of the present invention to provide a process for steam-sterilizing an adsorbent for use in extracorporeal circulation treatment comprising a water-insoluble support and a sulfated polysaccharide attached to the support without deteriorating the ability of removing harmful substances from body fluid such as blood.
Another object of the present invention is to provide a column for extracorporeal circulation treatment use having an improved storage stability, which is packed with a water-insoluble support/sulfated polysaccharide adsorbent and a packing fluid.
These and other objects of the present invention will become apparent from the description hereinafter.